new Promise((resolve, reject) => {
    setTimeout(() => {
        resolve('hello ');
    }, 10);
}).then(value => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve(value + 'lagou ')
        }, 10);
    })
}).then(value => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            console.log(value + 'I love you')
        }, 10);
    })
})